If you’ve had a brain injury, you need a sleep study because injury disturbs sleep. Even if you have no symptoms of disturbed sleep, it’s a good idea to have a study because we’re not always aware of the changes in our brain’s neurophysiology. For example, intense fatigue may not feel like it’s related to sleep, yet a sleep study can reveal subtle changes like multiple arousals aka waking up for two or three seconds at a time. You may not know you’re waking up for such brief moments, only that you’re fatigued all day and not rested in the morning. (Note: Fatigue after brain injury may have multiple causes, which are still not well understood.)
It’s important to have a complete picture of the damage from brain injury. Only a complete picture can lead to the best possible treatment program. Good diagnostics inform good treatments.
“Sleep disturbance is common following traumatic brain injury (TBI), affecting 30–70% of individuals, many occurring after mild injuries. Insomnia, fatigue and sleepiness are the most frequent post-TBI sleep complaints with narcolepsy (with or without cataplexy), sleep apnea (obstructive and/or central), periodic limb movement disorder, and parasomnias occurring less commonly.”Mari Viola-Saltzman, D.O. and Nathaniel F. Watson, M.D., M.Sc. Traumatic Brain Injury and Sleep Disorders. Neurologic Clinics. Volume 30, Issue 4, November 2012, pp 1299-1312.
A few of the sleep problems experienced after brain injury:
- Increased sleep onset latency, that is, taking too long to fall asleep.
- Not enough sleep.
- Waking up one or more times during the night for prolonged periods yet being far too tired to get up.
- Decreased sleep efficiency, that is, the ratio of total time asleep to time in bed.
- Increased wakefulness.
- Increased alpha-wave intrusions.
- Increased or decreased amount of time in each of the four stages of sleep (note: some Americans have shrunk the four stages of sleep to three, but four provides a better picture of sleep).
- Increase or decrease in the amount of total slow-wave sleep, that is, delta brainwaves during sleep.
- Increased or decreased amount of time in REM sleep.
- Periodic limb movements. Periodic limb movement disorder occurs during sleep only. Restless leg syndrome includes limb movements when also awake and occurs as an urge to move the limbs in response to discomfort. Limb movements can lead to arousals.
- Arousals, that is, an abrupt change in brainwave patterns. Instead of going through the stages of sleep, you zip from one stage to another, skipping the in-between stages. Arousals can be spontaneous, from limb movements, or requiring effort to breathe.
- Respiratory effort-related arousal (RERA) that lasts longer than 10 seconds but isn’t considered partial or complete obstruction of breathing as happens with hypopnea or apnea.
You may not be aware of arousals for they’re brief in nature. If your arousal goes from stage 4, slow-wave sleep, to wakefulness, you may end up sleepwalking. I did not.
Types of Sleep Studies
This is the classic sleep study done in a sleep clinic or hospital. Polysomnography records your brainwaves (electroencephalogram or EEG), your heartbeat and heart rate (electrocardiogram or ECG), your leg movements, your body positions, your oxygen saturation in your blood, eye movements, and your breathing during your entire night-time sleep. The sleep study may continue on into the day to study daytime sleep by asking you to nap a few times for a set amount of time each time (see Multiple Sleep Latency Testing below). The study also includes a video and sound recording of you.
Polysomnography gives the specialist an objective picture of exactly how you sleep, notwithstanding the huge distractions inherent in the process. Huge distractions are from having electrodes cemented on your scalp with paste so stiff that it will prevent the electrodes being pulled off during tossing and turning; from two prongs under your nose; from straps around your face and your chest; from wires down your body to your legs; and from the cabling of wires from the electrodes on your scalp being plugged in to hardware next to the bed. Plus being able to hear extremely loud snoring men through soundproofed walls.
When you’re booked for a sleep study, you’ll be given information on what not to do beforehand and what to bring with you. The sleep study will include questionnaires to be filled in before and after the night recordings. What you won’t get is a sheet on what to expect and what it’s like. Click here for details of what it’s like as I described it at jeejeebhoy.ca. All provinces cover this test through medicare.
Multiple Sleep Latency Testing
This test may be added to the classic polysomnography. It’s used to test for narcolepsy and idiopathic hypersomnia. After you’ve completed the night-time study, you’ll remain in the clinic to measure your daytime sleepiness. At regular intervals, you’ll be put to bed for a nap to measure how long it takes you to fall asleep while recording your brainwaves, breathing, etc. You will be awakened after sleeping 15 minutes. If you do not fall asleep within 20 minutes, they’ll stop that nap. They’ll have you fill in questionnaires. You’ll have to find a way to keep yourself occupied in the intervening time between naps; you won’t be allowed to sleep between naps. This test is covered by medicare.
Actigraphy uses a watch-like device that measures your activity levels, your sleep, and sleep-wake cycles over a long period of time. However, it doesn’t record what’s going on in the brain. It’s a good addition to polysomnography. The technician straps the watch on your non-dominant wrist. You keep it on until you return to the clinic where they take it off. I had this test done as part of research. It may or may not be covered by medicare otherwise.
Home Sleep Apnea
This is a test specifically for sleep disturbed by stopping breathing. Sleep apnea is one of the well-known sleep disturbances and occurs with or without brain injury. If there’s concern you have sleep apnea without brain injury, this may be a good one to have, assuming your province or insurance covers it. But for those with brain injury, polysomnography is preferred over this one. A sleep study in the clinic will pick up on sleep apnea and, as well, give you the best picture of the totality of your sleep.
Why Get a Sleep Study?
I have heard many with brain injury are not given a sleep study. This perplexes me. Sleep is critical to recovery. And brain injury affects sleep. How it does differs from person to person. How bad it is can’t be determined from a questionnaire. You need to study it objectively in order to understand why waking up is hard to do, fatigue riddles the day, and whether such things as naps are good or bad.
- REM sleep changes
- Alpha wave intrusions
- Movement through the four stages of sleep
- Length of time in each stage of sleep
- Sleep disorders like periodic limb movement disorder
- How long it takes to fall asleep
- Number of microwakes, that is, arousals for seconds you’re unaware of
- Number of full arousals
- Number of respiratory effort related arousals
- Number of arousals from stage 4 or slow-wave sleep (an indication of possible sleepwalking)
- Sleep apnea
- Total time asleep
- Sleep efficiency
- Breathing patterns
- Oxygen saturation
- You’ll have an objective picture of your sleep.
- You’ll understand why you can’t fall asleep, why it feels like you’re not sleeping, and why you’re tired in the morning.
- You won’t get treatment for it under standard medical (non-)care of brain injury. So why do it? Because having an objective picture and understanding the why counters the skeptics, proves that your bad sleep is inhibiting your recovery, and can be used to assess the effect of neurostimulation treatments on your sleep.
In Ontario, OHIP will pay for an in-lab sleep study once every two years. Followup sleep studies could be useful in assessing the effectiveness of audiovisual entrainment (AVE) and cranioelectrical stimulation (CES) on falling and staying asleep. These are self-prescribed methods to aid sleep. In the future, specialists well versed in objective diagnostic tests and neurostimulation therapies will be able to prescribe and tailor programs to your specific issues that the sleep study reveals.
For further information on what kinds of information the sleep study will give you, you can read about my sleep study results on my website. Or pick up a copy of Concussion Is Brain Injury: Treating the Neurons and Me. Or ask for it at your library.